1. Field of the Invention
This invention relates generally to power driven drain cleaners and more particularly to power driven sewer snakes with safety overload clutches to prevent breakage or damage to the sewer snake.
2. Discussion of the Prior Art
The concept of power driven snakes for cleaning out clogged drains or sewer pipes is well known. Generally, an elongated flexible sewer snake which is formed of one or more helical wires is inserted into the drain pipe to be cleaned and at the same time rotated either by hand or most generally by an electric motor. A sewer or drain cleaning head is attached to the forward or free end of the flexible snake in order to cut away or clear the clogged portion of the drain pipe. A number of different types of cleaning heads are utilized depending upon the type of obstruction encountered. For example, a special cutter might be employed to cut through root obstructions, whereas a simple spiral shaped cleaning head might be utilized to force clogged material of a different type through the drain pipe. Most sewer snakes are adapted such that the sewer cleaning head may be readily changed to meet the particular situation.
A common problem which occurs in the use of power driven sewer snakes is breakage of the sewer snake itself or otherwise severely kinking the sewer snake such that it will not properly work due to the application of excessive torque being applied to the snake by the motor drive when the cleaning head or cutting head encounters an obstruction which severely limits or stops its rotational movement altogether. In this situation, severe torques are being applied to the long flexible snake because the cleaning head is not rotating at all. This excessive torque applied by the motor drive commonly causes the snake to permanently kink or completely break and sever, not only thereby rendering the sewer snake permanently damaged but generally the sewer cleaning head itself and a portion of the snake will remain in the sewer line being cleaned thereby further clogging the sewer line and creating the difficult problem of attempting to retrieve the broken off portion of the sewer snake from the sewer or drain pipe.
A number of attempts have been made in the past to eliminate this problem by providing a slip clutch at the power driven end of the sewer snake which permits slippage between the motor drive and the sewer snake when a predetermined torque has been attained. Examples of such devices are illustrated in U.S. Pat. No. 3,742,548 issued on July 3, 1973 and in U.S. Pat. No. 3,574,878 issued on Apr. 13, 1971.
While such slip clutches do decrease the possibility of breaking or otherwise damaging the sewer snake when the sewer cleaning head becomes jammed, they fail to eliminate the problem.
The reason for this is that as large lengths of sewer snake are being fed into the sewer or drain pipe, it is obvious that the total weight of the sewer snake itself being fed into the drain pipe also increases. It is accordingly further obvious that it takes more torque to rotate the sewer snake within the drain pipe with increased lengths.
In addition, as the sewer snake is being fed into the drain pipe, it also encounters many minor obstructions such as bends or turns in the sewer pipe itself which applies additional resistance to rotation of the sewer snake in proportion to the length of snake fed into the sewer or drain pipe. This also demands that additional torque be applied to the driven end of the sewer snake merely to keep the same rotating within the sewer or drain pipe.
The safety overload clutches of the prior art are generally a spring loaded type clutch wherein the torque setting at which the clutch will begin to slip may be preadjusted. These clutches are mounted adjacent the rotary motor drive so that they are easily accessible to the operator and may be periodically adjusted to change the torque setting at which they will begin to slip.
As previously indicated, as more snake is fed into the sewer line, more torque is applied to the sewer snake itself, and the result is that the safety overload clutch begins to slip. At this point, the operator stops the sewer snake motor drive and adjusts the safety overload clutch at a higher torque setting. The operator then starts the motor drive again and begins to feed additional snake into the sewer or drain pipe until such time that this occurs again, and the clutch begins slipping even though the sewer cleaning head at the free end of the snake has encountered no obstruction within the sewer line. Thus, again, the operator adjusts the clutch at an even higher torque setting to keep the sewer snake rotating even though no real obstruction has yet been encountered. It can be readily seen that this sequence of events repeats itself over and over until such time that the cleaning head at the free end of the snake finally does encounter an obstacle or obstruction which prevents the cutting head or cleaning head from rotating at all. However, by this time, the torque setting on the safety overload clutch is set so high that the sewer snake either permanently kinks so that it is no longer usable, or snaps or severs in any event, leaving the most difficult task of attempting to remove the broken portion of the snake and the cutter head or cleaning head from the sewer line. Not only is the cost of the sewer snake itself lost, but also the expense incurred time-wise in retrieving the broken snake from the drain pipe.
It is the principal object of the present invention to eliminate the aforesaid disadvantages of the power driven sewer snakes of the prior art.